Will start with chock on but wont stay running with it off

I'm sure you have dirt in your carb. If you know how to take the carb apart......You need to get a can of carb cleaner and carb kit. Take the carb apart and spray every hole and nook a crany you can see. Put the new kit in the carb and you should be ready to go!! This has happened to several times.

Sounds like the carb needs to be adjusted by someone that knows how to repair engines. Note: if the carb is set too lean, it will damage the engine.

check the fuel filter to see if its dirty or not under fuel . also you will have to re-tune the carb . or check for compression in the engine it should be at 120 or above you may also want to change the plug

your running out the gas in the carb out you need to rebiuld the carburator probably dirt in the carb from bad gas

Before pulling the carb apart, drain the fuel fit a new filter in the fuel tank, check the fuel hoses up to the carb for splits, cracks or leakage, replace if required.

Your problem sounds more like it's in the carburetor rather than in the petcock. If the petcock were bad, the carburetor would not be getting any fuel at all. It sounds like the slow speed jet in your carb or the small passageways in the carb are plugged up. They can only be cleaned by soaking the carb in a solution of professional grade carb cleaner after complete disassembly of the carb. The choke retracting on it own is not uncommon. There is an adjustment on the backside of where the cable is mounted to the bike just on the backside of the bracket. Tighten the thumb nut up to put more pressure on the choke cable. But, if the cable has ever been lubricated, this may not help much.

Good Luck
Steve

It wont be flooding because of a stuck choke, It would be a stuck float and float needle jet, so you may still need to clean the carb

sticky choke maybe, try carb cleaner, check the air-cleaner filter,depending on were you live, maybe some dry gas.from the symtom's sounds like it's chocking out,those are the easy cheap thing's first, now check the fuel filter, then the fue pump, prividing your getting good spark to fire up the fuel,good luck

I have an 01, and it started doing this. I don't remember the circumstances. It's just dirty in the carb I think.

1) Check for water in the gas.
2) Turn off the petcock and drain the carb. turn it back on.
3) Try it.
4) Start it with the choke on and put your hand over the air filter hole. Will cause some back flow.
5) Try again.

Worked for me. Might be dirtier on yours, or have mud in it or something.

If you have a compression gauge, check the compression. Anything under 90psi is too low.

Check your flywheel key. If it is broken the flywheel will move and not fire at the correct time.

Note: if it does not sputter with carb cleaner then it's not your carb.

Next:
Remove your exhaust manifold. Look into the cylinder with a flash light. You are looking for scratches. Anything larger then a light fingernail is definite proof you need a new cylinder/piston assy.

If it passes that test do the following:

Pour mixed fuel straight into your cylinder until 1/4 full. Slowly pull your saw over while looking into the cylinder. If you see bubbles after the ring/rings go by then you need a new cylinder/piston assy. On rare occasions if no scratches are present on the cylinder wall or piston, you may be able to change just the rings.